Method and means for detecting imperfectly sealed containers of vacuum-holding type



June 27, 1950 w. D. BELL 2,910

A METHOD AND MEANS FOR DETECTING IMPERFECTLY SEALED CONTAINERS OF VACUUM-HOLDING TYPE Fil'ed Feb. 14, 1947 3 Sheets-Sheet l M M M D. Bell 71717 I [am June 27,1950 w. D. BELL 2,512,910

METHOD AND MEANS FOR DETECTING IMPERFECTLY SEALED CONTAINERS 0F VACUUM-HOLDING TYPE Filed Feb. 14, 1947 5 Sheets-Sheet 2 FIG 5,

- William .3 Bell awn/my June 27; 1950 w. D. BELL ,5 2 10 METHOD AND MEANS.FOR DETECTING IMPERFECTLY SEALED CONTAINERS 0F VACUUM-HOLDING TYPE Filed Feb. 14, 1947 5 SheetsSheet 3 awe/WM William D Bell WWW Patented June 27, 1950 UNITED STATES PATENT OFFICE METHOD AND MEANS FOR'DETECTING IM- PERFECTLY SEALED CONTAINERS OF VACUUM-HOLDING TYPE William D. Bell, Columbus, Ohio; Helen L. Bellexecutrix of said WilliamD. Bell, deceased Application February 14, 1947,'Serial'N0. 728,612

5 Claims. 1

This invention relates to method and apparatus for determining the presence of vacuum in sealed containers. It has to do, more particularly, with a method and apparatus for marking sealed containers in an automatic manner when such containers do not possessan internal vacuum of required degree.

Many food-stuns are subject to deterioration when exposed to-oxygen of the atmosphere. For this reason, it is a current practice'on the part of many food processors and packers to place food stuffs in sealed-containers in which a, commercial vacuum is present, this being done for the purpose of excluding atmospheric oxygen and preserve the food stuifs indefinitely while they are retained in the containers during shipment and storage and prior to the opening of the containers by their ultimate users.

In producing such vacuum conditions in sealed containers, itiscustomary to introduce regulable quantities of steam into the head spaces of such containers prior to the final capping thereof, or in another process, asset forth in my prior Patent No. 2,284,631 granted June 2, 1942, to produce combustion of combustible gases in confined regions around the head spaces of such containers, and when combustion conditions reach a peak to seal the containers by applying the closure caps thereto.

While these methods are in the main effective in the vast majority of operations, itsometimes happens that imperfection in the glass bodies of the containers, or in the constructiono'f the metallic closure caps and their gaskets, or in the sealing operation itself, will result in leakage of air into the containers, thereby eliminating the desired vacuum in the head spaces of such containers, or impairing the vacuum to such a degree that food spoilage may result. The presence or absence of a vacuum (by which is meant a commercial or partial vacuum) in the head space of a container may be manifest in several Ways, such as noting the depression of the metallic cap or closure, or the audible sound 2. in, and Iemploy such variance to determine the degree of vacuum by noting the rate at which the head space will absorb and/or reject heat. It is, therefore, an object of this invention to provide a method and means of making this determination and to mark the defectively sealed containers unmistakably so that they may be removed from a group of containers prior to final packaging and shipment thereof.

It is another object of the invention to provide a novel method and means for marking sealed containers which may be readily adapted to production methods of packaging a number of such containers boxes'or cartons, and wherein the containers, while positioned in such boxes or cartons, and moving along a conveyor line, are marked individually'and automatically when improper "vacuum conditions obtain therein, or when vacuum. is entirely absent.

A further object of the invention is to provide a method and means for marking defective vacuum sealed containers having removable caps formed from heat-conducting materials, and wherein the caps are subjected successively to determined intervals of heating and cooling, and to which caps there is :applied indicators of a composition which, when heated to a predetermined" temperature, will apply a mark, or other graphic designation to the caps of containers whichar'e imperfectly sealed.

In the accompanyin drawings, I have illustrated apparatus whichmay be used in carrying out the present invention. However, it i to be understood :thatthis apparatus may take various forms as longv as it embodies the basic features of .my invention. In the drawings similar characters of reference designate corresponding parts, and:

Fig. 1 is aside elevational view of apparatus employed by the present invention in the marking of improperly or "defectively sealed vacuumtype containers;

Fig. 2 is a top plan view of the apparatus;

Fig. 3 is a detail side elevational view, partly in vertical section, of the container-marking mechanism utilized by'mypresent invention;

liig. 4 is a fdetail end' elevational view of the apparatus disclosed in Fig. 3, with associated parts intransverse cross section;

Fig. 5 is a side elevational view of the marking m'echanism1-and disclosingthe latch elements thereofin their: released positions;

Fig. 6 is a vertical transverse sectional view onthe line 6-6 of Fig. 1; 1

Fig. '7 isan'enlarged vertical transverse sec- 3 tional view taken through a vacuum sealed container of the type to which the present invention is particularly applicable;

Fig. 8 is a detail perspective view of one of the latch devices carried by the marking mechanism;

The apparatus illustrated comprises a frame structure composed of a plurality of longitudinally spaced and vertically extending legs ID, the

latter at their upper ends being united with a' pair of transversely spaced. and longitudinally extending horizontal rails II. Journaled in the ends of this frame structure are shafts l2 carrying pulley wheels l3, around which passes an endless belt or apron conveyor l4. Preferably, the rails II also act to support a plurality of transversely extending idler rolls I5, which are placed immediately beneath the upper run of the belt M for the purpose of supporting the latter and the products arranged thereon and advanced thereby. One of the shafts l2 may be driven by a motor 16, or other driving element.

Adapted to be positioned on the upper run of theconveyor belt for longitudinal advance along the machine in a guided course or way are paperboard boxes or cartons ll, the latter being of the usual commercial variety having open tops which are adapted to be closed by foldable side and end flaps l8 and I9, respectively. Each of these boxes or cartons is adapted to receive a group of closely packed sealable containers 20. While my invention is not so restricted, each of these containers may be of the type comprising a glass jar or body 2|, formed with an open top for the reception of food stuffs or other perishable substances. Such a glass jar, for example, may hold approximately 4 /2 ounces of a food product when filled to within one-fourth of an inch of the open top thereof. This top is then closed and sealed by means of a, thin metal cap, indicated at 22, which may be approximately 43 mm. in diameter. During the sealing operation, a vacuum of 20 to 24 inches Hg or more is produced in the head space 23 of each container, that is,'the space between the food products packed in the container and the under surface of the metal cap.

With the entire package at approximately room temperature, application of heat to the metal caps will result in thermal changes in the head spacesof the containers, depending upon the degree of vacuum present in such head spaces. The lower the pressure in the head spaces, the lower the vaporizing point of the moisture in liquid form on the inner. surface of the closing cap; also, the rate of heat transfer from the cap to the contents of the container will be correspondingly reduced. Accordingly, the metal cap or closure will, with a relatively high vacuum in the head space, respond more rapidly to ap-, plied heat since more heat is retained in the cap itself and less loss by radiation and conduction to the atmosphere of the head space and to the contents of the contained than would occur if a conducting atmosphere, were present in the head space and the vaporizing temperature higher. The same conditions, acting in reverse, cause the cap to cool more rapidly, when the under side thereof is exposed to a desired vacuum; after the source of heat is removed.

If the cap and head space of such a container is exposed to a source of radiant or convected heat, the rate at which the cap will heat, or the amount of heat which the cap will absorb, will be determined by the, conductivity and thermal capacity of the atmosphere within the head space of the container. In like manner, the rate at which the cap will cool after being heated as above, will be determined by the amount of heat that has been absorbed by the cap and the atmosphere of the head space during the heating period. Therefore, by carefully controlling the rate and time of heating, and by determining by one means or another the temperature of the cap after a definite cooling interval, the density of the atmosphere of the head space can be determined.

In the operation of a typical production line, as employed in food-packing establishments, the jars or containers 20 are filled with raw or partially cooked food stuffs. The metallic lids, caps or closures, shown at 22, are applied and vacuum created in the head space. The containers may then be processed under appropriate conditions of heat and pressure to sterilize the contents. After cooling, labels are applied and the containers are placed in the shipping boxes or cartons l i in which they are ultimately shipped. In acordance with the present invention, just prior to the final closing and sealing of the cartons for shipment, the individual containers are checked to make sure that a proper vacuum exists in the head space of each container. Usually the container are closely packed in the boxes or cartons in rows of six, making thirty-six containers within each box or carton. Such a box or carton is then placed on the conveyor M, with its side and end flaps held in outward horizontal positions, so that the top of the-box or carton is completely open to expose the metal-caps of the containers 20. The side flaps of the boxes or containers are positioned between stationary guide rods 24, so that they will be positively retained in approximately horizontal positions while the boxe or cartons are moving with the conveyor belt in the direction indicated by the arrow A in Fig. 3. Corresponding guide rods 25 may be suitably supported by the frame structure of the conveyor for the guidance of the boxes or cartons.

Arising from the framework of the conveyor are-stationary standards 26, four in number. These standards effect the support of transversely extending rods 27, on which are pivotally mounted for swinging movement the upper ends of a plurality of arallel links 28, the lower ends of said links being pivotally connected as at 29 with a horizontally disposed frame 39 of a heating mechanism H. One of the rods 2'! may be provided with a fixed quadrant 3| having formed therein an arcuate slot 32, this slot being adapted for the reception of a threaded bolt 33, carrying a wing nut 34. By this construction, the frame 39 of the heating mechanism may be raised or lowered with respect to the top of the containerfilled boxes or cartons moving therebeneath on the conveyor. 7 7

While the heating mechanism may take one of several'forms, I preferably provide the frame isregard I containers are used by slight experimentation and adjustments, such 'as-bydetermining the:

proper distance between-the resistor strips and the tops of the-containers, the rate of' linea'r' ad-- Vance of'the' conveyor, and the le'ngth o'f-each of the resistor strips. These, of course, are practical factors which may 'be-readil'y-determined to best advantage by-=a skilled -w'orker in the-art.

"Theconve'yor blt isdriven-continuou'sly at a constant rate of speed, 's'o tha't' after a givenbox holding -'the containers travelsp'as't the heating mechanism H, i the box-will enter a cooling zone C, in which areduction in temperature on the'p'art of the containers andtheirheat'ed "metallic caps takes place, this cooling'period'being ofadefinite or -'determi ne'd duration, so that theproperly sealed containers, in which a desired degree of vacuum is present, will attain "a somewhat lower temperature than in containers which areim'-- properly sealed, that-is; in which a lower degree of vacuum or atmospheric pressures are =presthe upper 'ends -o fsets' of parallel links 3 8,'the

lower ends-of these links beingpivota11y joined as as 39 to the rectangular frame-40 of the marking mechanism. This frameoccupies a substantiall'y horizontal position 'abovethe boxed con tainers moving" with the'upper run of the 'con veyor belt, but the mounting of the frame'is suchthat the same may be moved vertically toward and-away from the tops-of the boxed containers. Normal-1y theframe is maint'ainedin arelatively elevated position by providing one'of the cross rods 31 with a fixed" arm 41,-and securing to the outer end thereof a-spring 4'2, the opposite end of the spring being connected with one of the links' 38. Unless'otherwis'e influenced, as will be hereinafter explained, the spring 42 serves to maintainthe frame in its relatively elevated position.

The frameflo is'formed'with a plurality of upstanding bosses '43, each of tl'i'e'latter being'formed with'an axially disposed'ope'ning or bore 44 which.

whenthe frame is'lowered, is adapted forvertical and axial registration with one of the containers 20. Slidablypositioned in each of the openings 44 "is an indicatorpencil 45. Each pencil advantageously may comprise a-solid rod-like body 46 which carries at'the lower end thereof a fusible crayon-like marking portion "4". The lowerends of the marking portions of these'indicatingpenoils are adapted 'tocontactthe center of each container lid or cover, and the material fromwhich the marking portion is formed is carefully selectedso that it will soften, 'fuse-or melt in' ver y close t'emperature'limi'ts. This-range is such that the hotter container'lids or caps, present on imperfectly sealed containers, will possess a temperature sufficient upon momentary contact of the pencils therewith to soften the lower ends of the marking portions of the pencil and cause the same to produce a mark or spot in the center of the lids or caps possessing abnormally high temperatures. The perfectly sealed cans or containers, having lids or caps at lower temperatures, will not soften or fuse the pencil ends and,

therefore", will not *be' marked thereby. Aiftefl' the b'oxed containers pass out of registration-with the marking mechanism, -a-' marked container 1 or containers may bere'a'dily noted by an attendant, removed fromtnepox andaerfecfly sealed con-- tainerwr'containers substituted therefor.

' Tocompens'a-te' for pencil wear, the "rod-like bodie's fifi-thereof are received inclamping rings 8 Theseringshave their under surfaces engaged with the upper ends of fulcrumpins- #9 carried *by and projecting upwardly from the bosses =13. Opposite to 'the pins-4B, tl'ic' under surfaces of the rings 48 engage with the upper ends-ofvert'ically movable stems 5'6, These stems are steamy mounted in vertical openings 5 I providzadthereiforinthe bosses, and the lowerends' of'the 'st'erns positioned toeng'agewith the caps or lidsof' the containers "20 as shown in Fig. '3;

Normally, the headed upper 811215 52 of the stems 50* are positioned in sockets 5-3'provid'ed-therefor at the 'u'pp r ends of the openings 5|,so that-the clamping rings 48- are somewhat singularly posi-* tioned with relation to the horizontal *for the purpose of gripping the'rods ofthe marking'penci'ls and holding the same against vertical move merit. However, as the pencils wear downas a result of use; this conditionis compensated for by the-presence of the'stems 5U which a-s' stated, when the frame it is lowered, will contact the container lids, causing the clamping ringsto be rocked 'on their fulcrum pins t9 and; releasing themarking-pencils' so that their lower ends will contact the container lids. 'When the frame 40 moves upwardly, thest'ein'sd'rop downwardly, releasing "the clamping'ringsand enabling the same to"grip"thefrod-like bodies of themarkingpencils, thereby'retainingthe lattera'gainst descent,

irrthe'opening dfiofthe bosses 43.

To'effect the swinging movement of the frame of the markingunechanism, so that th'e'marking pencils brought into and out of engagement with the container lids 01' caps, the rear end of the frame 5% carries a dog 54 at eachside thereof. j

Each'of these" dogsis'pivotally mounted as'at55 on a"base plateetsecured to the'frame 48; 'Each dogis further formed with a laterally "directed rectangular" plate extension 5''! and an offset weight 58', the tendency of theilatter being to so rock'e'ach' of the dogs that the plate extension thereof will bevertically positioned'and disposed in'thepath of movement of the side flaps Hlof'the'boxes H, as illustrated in Fig. 4. The dogs are held in this normalposition' by means o'f'fthe shoulders "59 of a pair of latches 60, the latterbeingpivotedasat'fi ion the base plates "58 and formed with laterally offset foot extensions SIa'.

Thus, asthe boxedcontain'e'rs advance with'the upper runof'theconveyor'belt M, and. are brought beneath and in vertical registration with the marking'mechanism,the forward end of the box oricar'ton, as shown in Fig. 3, engages with the plateex'tensions'm of the dogs '54', thereby swinging the frame '40 "of the marking. mechanism a'bfoiifithepivotal axesof the links 38,. and against markingmechanism and allowing the latter to return'to its normal elevated position in response to the action of the spring 42, the dogs 54 returning to their normal positions. After the conveyor moves past the marking mechanism, it may be viewed by an attendant who, by noting the marked caps on the product containers, may remove the containers of such marked caps from the box or carton and substitute therefor properly sealed and previously inspected containers. The flaps lBand [9 may then be folded and sealed in the usual manner and the inspected package is then ready for shipment.

It will be apparent from the foregoing description that I have provided simple and economical methods and means for facilitating the inspection of vacuum-packed containers. The invention readily lends itself to production systems for packaging a plurality of food containers or the like, and is reliable, effective and positive in oper-: ation. Many advantages of the invention have been discussed herein and others will be apparent.

I claim:

l. The method of determining the degree of vacuum in the head space of a container of the type having a removable lid formed from a material possessing high heat conductivity, comprising heating the lid end of the containerat a given temperature for a predetermined time, allowing the container and its lid to cool for a definite interval of time, and thereafter bringing into contact with the lid a marking compound which softens at a predetermined temperature as indicative of a defective seal.

2. The method of determining the degree of vacuum in the head space of a container adapted to receive food stuffs which are subject to de-.

terioration through oxidation and wherein the container i of the type having at its top a re-' movable cap formed from a material possessing good heat. conductivity, the steps which comprise: advancing a plurality of such containers while the same are positioned in closely grouped vertical order in a carton beneath a heating.

means capable of applying heat to the caps of the containers to cause the same to attain a predetermined temperature, discontinuing the application of heat to the caps and allowing the Q3. The method of detecting imperfectly sealed containers of the type adapted for the reception of perishablefoods and in which vacuum condi-j tions are maintained in head spaced provided in the containers between the foods received therein and, removable caps covering the tops of the containers, the steps which comprise: advancing such containers longitudinally in a guided course 8a, of travel, during such advance of the containers subjecting the caps thereof to a heating instrumentality whereby to imparta given temperature tothecaps in a predetermined period of time, thereafter advancing the containers through a cooling zone and allowing the containers to cool in said zone for a period of definite duration,

and at the end of said coolingzone, bringing the caps of said containers into engagement with a fusiblemarking compound having a predetermined softening point, whereby to cause said compounds to produce a marking deposit on caps possessing a temperature in excess of a given or predetermined temperature.

4. Apparatus for detecting the presence and absence of 7 Vacuum in sealed containers of the typehaving removable caps, comprising a frame structure,'a conveyor for advancing such containers along a longitudinal course, means for supplying heat to the caps of said containers during advance thereof in unison with said conveyor, and means for applying a fusible compound to the caps of said containers following predetermined heating and cooling thereof, the softening point of said compound being such as to produce a, deposit of the compound on container caps possessing a temperature in excess of that of a predetermined temperature, the latter temperature being below the softening point of said compound.

5. Apparatus for determining the degree of vacuum in the head space of a container sealed by aremovable'cap, comprising a conveyor adapted to receive 'a carton in which a plurality of such containers are arranged in closely adjacent rows, said cartons being of the type having foldable side flaps, guide means arranged adjacent to said conveyor for maintaining said side flaps in open substantially horizontal positions, electrically energized heating means mounted adjacent to said conveyor immediately above the tops of the containers positioned in said cartons, whereby during advance of the cartons in unison with the vconveyor, the said heating means will serve to impart a predetermined temperature to the upper endsof said containers, a vertically movable frame'mounted above and adjacent to said REFERENCES CITED The following references are, of record in th file of this patent:

UNITED STATES PATENTS Number Name Date 1,485,895 Thompson Mar. 4, 1924 2,020,676 Ellis Nov. 12, 1935 2,208,202 Stanton et a1. July 16, 1940 

